An OLED architecture is described in which a thin emitter layer is located at the anti-node of a resonant microcavity. In two realizations, the mode space is constrained by either multi-layer mirrors or by an emitter with transition dipole moments oriented normal to the vertical mode of the device. The multi-layer mirror device achieves 315 lm/W and the oriented emitter device achieves 340 lm/W. Output is observed to be linear in current and efficiency increases with power. This is in agreement with a proposed theoretical model for a microcavity device with emitter located at an anti-node where spontaneous emission is suppressed.